Do not assume /DUNICODE and /D_UNICODE.

As a library, WebRTC should not assume UNICODE and _UNICODE to be
defined globally.

This CL explicitly selects wide character functions and types in
order to build WebRTC with /UUNICODE and /U_UNICODE.

Bug: None
Change-Id: Ie4e2bcb4c5c34aee6f68dc7b5b54b76f088ee3e4
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/128904
Commit-Queue: Tommi <tommi@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Reviewed-by: Noah Richards <noahric@chromium.org>
Cr-Commit-Position: refs/heads/master@{#27313}
diff --git a/test/testsupport/file_utils.cc b/test/testsupport/file_utils.cc
index 45b2bc2..b3ef0eb 100644
--- a/test/testsupport/file_utils.cc
+++ b/test/testsupport/file_utils.cc
@@ -104,8 +104,8 @@
 std::string TempFilename(const std::string& dir, const std::string& prefix) {
 #ifdef WIN32
   wchar_t filename[MAX_PATH];
-  if (::GetTempFileName(rtc::ToUtf16(dir).c_str(), rtc::ToUtf16(prefix).c_str(),
-                        0, filename) != 0)
+  if (::GetTempFileNameW(rtc::ToUtf16(dir).c_str(),
+                         rtc::ToUtf16(prefix).c_str(), 0, filename) != 0)
     return rtc::ToUtf8(filename);
   assert(false);
   return "";
@@ -143,8 +143,8 @@
     path += '\\';
 
   // Init.
-  WIN32_FIND_DATA data;
-  HANDLE handle = ::FindFirstFile(rtc::ToUtf16(path + '*').c_str(), &data);
+  WIN32_FIND_DATAW data;
+  HANDLE handle = ::FindFirstFileW(rtc::ToUtf16(path + '*').c_str(), &data);
   if (handle == INVALID_HANDLE_VALUE)
     return absl::optional<std::vector<std::string>>();
 
@@ -154,7 +154,7 @@
     const std::string name = rtc::ToUtf8(data.cFileName);
     if (name != "." && name != "..")
       found_entries.emplace_back(path + name);
-  } while (::FindNextFile(handle, &data) == TRUE);
+  } while (::FindNextFileW(handle, &data) == TRUE);
 
   // Release resources.
   if (handle != INVALID_HANDLE_VALUE)